<html>
<head>
    <meta http-equiv="Content-Type"  content="text/html;charset=UTF-8">
    <script type="text/javascript">
            function javaCallJs(message){
                alert(message);
            }
        </script>
</head>
<body>
<button type="button"
        style="font-size: 50px;"
        onClick="window.main.jsCallJava('Message From Js')" >
        Js Call Java
</button>
</body>
</html>